Immunological and health-state parameters in the Patagonian rockfish Sebastes oculatus. Their relation to chemical stressors and seasonal changes.

SUEIRO, M. C.; AWRUCH C. A.; PALACIOS, G.

Buenos Aires

Congreso; 11th Biennial Meeting Society of Environmental Toxicology and Chemistry; 2015

Fish inhabiting urban andindustrialized coastal areas are often exposed to high levels of complex mixesof anthropogenic pollutants. This exposure can lead to decreased disease resistance,with immunosuppression hypothesized as the main mechanism by which toxicantsmediate this decline. We present initial results of a field study thatevaluates whether exposure to anthropogenic pollution impacts immunological andhealth-state parameters of wild marine fish in the Peninsula Valdes region (anUNESCO Natural World Heritage area) during the breeding and non-breedingperiods. We assessed aspects of constitutive innate immunity (bactericidal competence,natural antibodies, and leukocyte profile) and some general health-relatedparameters (neutrophil to lymphocyte ratio, hematocrit, and condition factor) inthe rockfish Sebastes oculatus. Individualswere sampled from polluted (exposed) and reference (control) sites during winter(i.e.active reproductive period) and in summer (i.e.  non-reproductive period). Results showed that bactericidalcompetence, hematocrit, and condition factor were lower in fish from exposedsites independently of season. However, we found that fish sampled duringwinter displayed lower values of bactericidal competence, hematocrit, andcondition factor independently of site. There was no effect of site or seasonon the percentages of neutrophils and monocytes, whereas lymphocytes werehigher at the exposed site only during summer. Natural antibodies were notaffected by site, but showed differences between seasons, being higher duringwinter. The mechanisms involved in altered immune and health-related parametersassociated with living in polluted sites could be elicited by toxicantsdirectly, by stress hormones indirectly, or by a combination of both.  Our results could be explained by life-historytheory, which predicts a trade-off between reproduction and immune defense, andthus, lower immune investment during the most energetically demanding season (i.e.,active reproduction and thermally challenging period). Nevertheless, naturalantibodies showed the opposite pattern. Our findings indicate an alteration in immunologicaland health-state parameters of wild marine fish exposed to anthropogenicpollution, which could potentially result in a lower ability to fight disease. Themechanisms involved in altered immune and health-related parameters associatedwith living in polluted sites could be elicited by toxicants directly, bystress hormones indirectly, or by a combination of both.